The United States Border Patrol is viewed by many as the first line of defense against a threat of global terrorism and illegal immigration. The agents often sympathize with those they are charged to arrest, and there is very rarely a good guy/bad guy mentality. While they are often successful at what they do, border crossing is a cyclical pattern. As long as the United States represents an economic opportunity for Central and South Americans, there will be illegal crossings, and the agents will continue to patrol.

Standing on top of a truck, a Border Patrol Agent scans the horizon for groups of illegal aliens.

Border Patrol agent Chris McGrath searches the ground alongside a south Texas ranch-road for footprints, called "sign," left by groups of illegal aliens.

A Border Patrol Agent who declined to give his name looks over a group of suspected illegal immigrants found in a field along the U.S.-Mexican border outside Charrizo Springs, Tx.

A detained crosser.

Agent Martinez returns to his vehicle after a suspected trail turned up nothing.

Agent Clanahan finds a group of crossers that were "layed up" for the day. Groups often lay up or rest in thick areas of vegetation during the day and travel at night in order to avoid the Border Patrol. "If I was to put myself in their shoes, I might do the same thing trying to get a better life for my family, They're human beings just like anybody else." Clanahan said.

A group of apprehended individuals head out of the south Texas ranch where agents found them.

A truck waits to unload a new set of detained crossers in Carrizo Springs, Texas.

With an illegal alien in the back of the Sport Utility Vehicle, agent Delossantos rides back to the Border Patrol Station, where the apprehended man will be processed and prosecuted.

A detained man sits in a holding cell in the Carrizo Springs facility. From here he will be brought to a local court for further prosecution.

Agent McGrath follows a set of footprints into the Texas dusk. Despite their work there will always be more groups coming across.